Yeah no one gave a shit because it wasn't affecting their part of the world.
We also didn't care in 1976, 1977, 1979, 1989, 1990, 1992, 1994, 1995, 1996, 1997 and so on when there were small outbreaks.

It has been considered dangrous, it's just that no one's done anything about it. It's not that easy to cure something when you can't identify it's habitat/carriers.